Flow-injection detector incorporating a screen-printed disposable amperometric biosensor for monitoring organophosphate pesticides.
The construction of a wall-jet flow cell, which houses a screen-printed amperometric pesticide biosensor, together with a complete flow-injection system, is described. This system was initially employed in studies to stabilise the enzyme acetylcholinesterase (AChE), which was immobilised on a cobalt phthalocyanine screen-printed carbon electrode to form a biosensor. A combination of dextran sulfate and lactitol, and carbodiimide for enzyme immobilisation, resulted in biosensor lifetimes of at least 76 d (at 37 degrees C). Flow-injection and biosensor conditions were optimised, then the system was evaluated by monitoring the model organophosphate pesticides (OP) dichlorvos and paraoxon. The detection limits were 7 x 10(-11) mol dm-3 (for 1 U of AChE) and 4 x 10(-11) mol dm-3 (for 0.05 U of AChE), respectively, which are better than for other electrochemical methods. Initial evaluations on two river water samples have been carried out to test the validity of the system for OP determination in field samples.
Rippeth
J J
JJ
Department of Biochemistry and Molecular Biology, University of Leeds, UK.
Gibson
T D
TD
Hart
J P
JP
Hartley
I C
IC
Nelson
G
G
D015374:Biosensing Techniques; D005069:Evaluation Studies as Topic; D017022:Flow Injection Analysis / Q000295:instrumentation / Q000379:methods; D007306:Insecticides / Q000032:analysis*; D009943:Organophosphorus Compounds; D014874:Water Pollutants, Chemical / Q000032:analysis*
D007306:Insecticides; D009943:Organophosphorus Compounds; D014874:Water Pollutants, Chemical